Twenty-seven people, including 20 children, are dead after a shooting at Sandy Hook Elementary School.

Another person was found dead at 36 Yogananda St. in Newtown, sources told The Courant, and the gunman was found dead inside the school.

The shootings at the school took place in two rooms, one of which is a kindergarten classroom, sources said. One entire classroom is unaccounted for.

Students described being ushered from their classrooms hand-in-hand, with their eyes closed, to the safety of a nearby fire station as police converged on the school. Anguished parents rushed to the scene.

State police sources told The Courant that the shooter is 20-year-old Adam Lanza. When he was found, he had his brother Ryan Lanza’s identification, which initially led to confusion about his identity, police said.

He was dressed in black fatigues, police said.

A law enforcement official said the boys' mother, Nancy Lanza, works at the school as a teacher. The Associated Press is reporting that she is presumed dead.

A grandmother of the suspect — who is also the mother of teacher believed killed — was too distraught to speak when reached by phone at her home in Brooksville, Fla.

“I just don't know, and I can't make a comment right now,” Dorothy Champion, 78, said in a shaky voice as she started to cry. She said she hadn't heard anything official about her daughter and grandsons. She declined to comment further and hung up.

The gunman drove to the school in his mother's car, an official said. Three guns were found — a Glock and a Sig Sauer, both pistols, inside the school, and a .223-caliber rifle in the back of a car.

President Obama, in an emotional address to the nation Friday afternoon, said "These neighborhoods are our neighborhoods, and these children are our children."

“I know there’s not a parent in America who doesn’t feel the same overwhelming grief that I do," he said. "The majority of those who died today were children, beautiful little kids between the ages of 5 and 10 years old. … They had their entire lives ahead of them. Birthdays, graduations, weddings, kids of their own."

“Among the fallen were also teachers, men and women who devoted their lives to help their children achieve their dreams,” he said.

Three people were brought to Danbury Hospital. Their conditions are not confirmed. The emergency room is on lockdown.

State Police Lt. J. Paul Vance said two children died at a local hospital and another had injuries.

Shortly after 9:40 a.m., police reported that a shooter was in the main office of the school. A person in one room had “numerous gunshot wounds,” police said.

“A minute after our officers were there, they realized what a horrific scene we had there,” said Newtown Police Lt. George Sinko.

Once they know how serious the incident was, they called for help.

“This is most definitely the worst thing experienced here in town,” he said. “But for now, we’re concerned about the families of the victims.”

Groups of students — some crying, some holding hands — were being escorted away from the school by their teachers. Some students were still in the school at 10:30 a.m., parents said, as police searched the area.

Police were still searching the school at 11 a.m., and police dogs were brought in. Around noon, the triage area was broken down, stretchers were taken away and the SWAT team left the building.

Sandy Hook Elementary has nearly 700 students in kindergarten through fourth grade. Its doors are locked at 9:30 a.m., and visitors are required to sign in, according to the school's website.

School and local emergency officials were accounting for the children, who were released to their parents. Some parents were sequestered at the Sandy Hook fire department, directly in front of the school.

By 4 p.m., somber groups of families were leaving the firehouse, many accompanied by police or firefighters.

A temporary morgue was being set up in the area so that the victims could be positively identified as expeditiously as possible.

Earlier, frustrated parents were desperately trying to get information from officials as they searched the school.

Vanessa Bajraliu, a 9-year-old fourth grader, heard the shots.

"I saw policemen -- lots of policemen in the hallway with guns," she said. "The police took us out of the school. We were told to hold each others' hands and to close our eyes. We opened our eyes when we were outside."

Her brother, 17-year-old Mergim Bajraliu, a senior at Newtown High School, was at his nearby home when he heard shots, he said. He first went to a neighbor's house.

"Then we heard sirens," he said.

He rushed to the school on foot and saw a girl being carried out, he said. She looked badly injured. Another girl had blood on her face, he said.

Mergim soon found his sister and took her away from the scene.

Parent Richard Wilford said his Sandy Hook second-grader, Richie, heard what he described as “pans falling” when gunshots rang out. He said that his son told him that the teacher went to go check, came back in and locked the door and told the students to stand in the corner.

“What does a parent think about coming to a school where there’s a shooting … It’s the most terrifying moment of a parent’s life … you have no idea,” said Wilford.

Brendan Murray, a 9-year-old 4th grader, said he was in the gym with his class when they heard "lots of banging." He said the teachers put the students in a nearby closet where they stayed for about 15 minutes before police officers told them to leave the building.

The boy said the students ran down a hallway where there were police at every door. He said "lots of people were crying."

Eight-year-old Alexis Wasik, a third-grader at the school, said police were checking everybody inside the school before they were escorted to the firehouse.

"We had to walk with a partner," she said.

One child leaving the school said that there was shattered glass everywhere. A police officer ran into the classroom and told them to run outside and keep going until they reached the firehouse.

Audra Barth, who was walking away from the school with her first-grade son and third-grade daughter, said a teacher took first-graders into the restroom after bullets came through the window.

When Janet Vollmer, a Sandy Hook Elementary School kindergarten teacher, returned to her Liberty Street home around 4 p.m. Friday, her grown son and a nearby neighbor were there to greet her. The neighbor, who did not want to be identified, ran over as soon as she saw Vollmer and hugged her. The neighbor said she heard about the shooting at work and, “I kept hearing it might have been a kindergarten teacher. I was hoping it wasn’t her. I was shaking at work.”

When she learned that Vollmer was OK, “I was so relieved. This is too close to home,” she said.

The neighbor said she was so sad for all the families whose children died nine days before Christmas.

One of Vollmer’s adult sons came to the door of her home and said she didn’t want to talk.

Students at nearby Newtown High School on Berkshire Road were stunned Friday when they learned of the shootings.

Senior Alex Buttery said when she learned the shootings had taken place on Dickinson Drive — where the school is located — “I immediately thought of Sandy Hook,” she said. “It’s devastating.”

Buttery, walking out of the school Friday afternoon with her friend Clare Donnelly, said she’d cried a lot today.

Donnelly said “it’s hard to wrap your head around” the shooting. “It’s difficult to watch [young children] go through this.”

Junior Renee Henriques said she was “shocked, speechless” by the shootings.

Buttery said she had been texting back and forth with her mother all day. “I went there,” she said of Sandy Hook School. “I know the teachers. I’m just wondering who it is.” Her mother, she said, was very emotional. They “know a lot of neighbors who go to Sandy Hook.”

NHS student Stefanie Carr said she was having a hard time processing what had happened. “I just couldn’t process how I felt. I’m still trying to get over it.”

All of the students had the same question: “Why someone would do that to the children?”

James Dietter, 26, lives in the Yogananda neighborhood where a person was found dead. His mother works in the school system.

"This is the idyllic New England hamlet … there was a bit of a magical insulation or feeling that tragedy won't happen here. Now it has, and, unfortunately, I think it is going to define this town."

Several news outlets, including The Associated Press and CNN, initially identified the shooter as his older brother, Ryan Lanza.

CNN is no longer identifying the shooter.

One law enforcement official said Ryan Lanza had been extremely cooperative, was not believed to have any involvement in the rampage and was not under arrest or in custody, but investigators were still searching his computers and phone records. Ryan Lanza told law enforcement he had not been in touch with his brother since about 2010.

Marsha Moskowitz, a former bus driver in town, remembered the Lanza boys.

“You know the trouble kids, and you figure, ‘Pff, that one’s going to be trouble.’ But I never would have thought that about them,” she said.

Moskowitz ran into the boys’ mother a couple of weeks ago and exchanged peasantries, she said.

Newtown United Methodist Church opened the doors around noon after ministers there heard of the tragedy. Brad Tefft, a bereavement minister at the church, drove in and opened the doors.

He created a sign that said "prayer vigil," which he placed out by the street, and also put a sign on the door saying sanctuary open.

“The closeness became more apparent when you see a tragedy like this,” he said. “We all feel for the families, and the kids and the teachers. It’s part of who we are. It’s part of the fabric of what this community is like. When something like this happens it tears at all our heartstrings.”

As word spread of the magnitude of the tragedy in Newtown, Gov. Dannel P. Malloy talked on the telephone Friday with President Obama about the incident and held a press conference after Obama addressed the nation.

"Earlier today, a tragedy of unspeakable terms played itself out in this community," he said. "You can never be prepared for this incident."

"Beautiful children had their lives taken away from them, as well as adults whose responsibility it is to supervise and take care of those children," Malloy said.

Malloy spoke again Friday evening from the scene.

“Evil visited this community today,” he said. “It’s too early to speak of recovery, but each parent, each sibling, each member of the family has to understand that Connecticut, we’re all in this together, we’ll do whatever we can to overcome this event. We will get through it, but this is a terrible time for this community and these families.”

“Our prayers at this time have to go out to the families. ... The No. 1 way to be helpful is to say a prayer or send a best wish or to be thinking of these individuals who have suffered so mightily today.”

Earlier, Malloy spent time with the families, said Roy Occhiogrosso, Malloy's senior adviser.

"He is attempting to make sure they get the information they need. It is an unspeakable scene.''

Malloy ordered state and U.S. flags to be flown at half-staff.

In Washington, D.C., House Speaker John Boehner ordered flags at the U.S. Capitol to be flown at half-staff.

State officials reacted with shock and alarm to the shootings.

House Republican leader Larry Cafero and Senate President Pro Tem Donald Williams were both stunned upon hearing that 27 had been killed. Cafero put his hand over his mouth in an immediate reaction.

The state departments of public health, education, mental health and addiction services, and the state police are all working on the incident.

Incoming U.S. Rep. Elizabeth Esty, who represents Newtown as part of the 5th Congressional District, said, "As a mother, I can only begin to imagine what the students, parents, teachers and staff of Sandy Hook Elementary must be experiencing. My thoughts and prayers go out to everyone impacted by this horrific tragedy. While details are still emerging, I hope for the safety and well being of the children, teachers and staff at Sandy Hook Elementary and for the Newtown community.''

Incoming U.S. Sen. Chris Murphy arrived at the firehouse around 2:30 p.m. and went to talk with parents.

Afternoon buses and kindergarten were cancelled. The entire Newton district was put on lockdown, and other school districts took similar measures across the state.

In West Hartford, Superintendent Karen List sent a recorded message to families Friday noting an increased police presence at town schools after the Newtown shootings.

“It’s really for reassurance,” List said. Counselors will also be available for students at the schools, and West Hartford administrators are now creating a set of talking points for parents if they decide to explain the shootings to their children over the weekend.

A meeting of Farmington Valley-area superintendents that was scheduled for Friday was canceled.

“We need to be in our districts,” List said. “We need to be communicating with our families; we need to be supporting our faculty and children.”

Southington schools were placed on a precautionary “passive lockdown” in which exterior doors are locked, Assistant Superintendent Karen Smith said. “We’re asking all administrators to be vigilant and to be aware of what is going on.”

In Waterbury, Wilby, Crosby and Kennedy high schools have canceled Friday’s afternoon and night games, according to the school system. Other after-school activities for Waterbury schools will go on as planned, but there will be police on the premises.

Bridgeport Superintendant of Schools Paul G. Vallas has canceled all after-school programs except for the Central High School basketball game.

All Winterfest Hartford activities in Bushnell Park in Hartford will be closed today. The skating rink is closed effective immediately and will re-open tomorrow on regular schedule.

Schools in the Pomperaug Regional School District 15, based in nearby Southbury and Middlebury, were put on lockdown after the shootings, Superintendent Frank Sippy said. After-school and weekend activities were canceled.

“Everyone is searching for the reason why — why such a senseless tragedy has to transpire in this country,” Sippy said.

“We’ll take the weekend to reflect. I just think it’s time for people to step back and take a breath and spend time with loved ones,” said Sippy, who has offered the district’s services to Newtown schools.

The only mass shooting in the U.S. with more than 27 killed since the 1950s took place on April 16, 2007, when a student named Seung-Hui Cho shot and killed 32 people at Virginia Tech in Blackburg, Va., before shooting himself.

On May 18, 1927, Andrew Kehoe, school board treasurer in Bath Township, Michigan, bombed three schools, killing 38 children, two teachers and four other adults, as well as himself, because he was enraged by higher taxes to fund a new school.

Friday’s massacre may be the largest school shooting of young children in the world, said Larry Barton, a professor at the American College in Pennsylvania whose three decades of research includes studying violence in workplaces, public spaces and schools.

Mass school shootings have often targeted high schoolers, such as the victims of Columbine, and university-age students. And in China, there have been numerous cases over the past three years of knife-wielding adults attacking children, such as an incident Friday in the Henan province where a man slashed 22 children.

“This is among the most diabolical crimes, to kill kindergarten-age children,” Barton said of the Newtown case. “It’s very rare.”

Barton also teaches threat assessment at the FBI Academy in Quantico, Va., where one of the cases he presents to law enforcement is the 2010 Hartford Distributors Inc. rampage in Manchester. Omar Thornton, 34, fatally shot eight of his co-workers before killing himself.

“The most dangerous person in society is what we call the grievance collector,” Barton said. “It’s the person who has a grudge, who cannot let go of an issue. They become obsessed and they tend to be exceptional at both planning and documenting ...

“It will take weeks, maybe even months, to understand motivation. Often what the shooter is seeking is not just revenge, but notoriety,” Barton said. “They are seeking a sense of trying to eclipse prior perpetrators.”